"Accept" and "except" are homophones, meaning they sound basically the same, but have different meanings. This isn't a problem when speaking, because context usually makes the intended meaning clear. When you write, it can be difficult to remember which spelling goes with which meaning. If you pay attention to the word's position in the sentence and associate the word with similar words, it is easy to distinguish the two.
For most situations, you don't need to know what "accept" and "except" mean to use the right one. "Accept" is always a verb, and "except" is almost always a preposition or a conjunction. "Accept" is always an action; "accept" and "action" both begin with "a" and are performed by someone or something. You accept an award or a package. A business accepts credit cards. "Except" generally signifies no action, but it modifies an existing action or situation. You can eat everything except your vegetables. A business can accept every credit card except yours.
You can't always tell which spelling to use based on where the word is, because rare occasions exist when "except" is a verb. In these situations, remember the difference between "accept" and "except" by associating "except" with other words that exclude. To except something is to exclude it, to cause it to exit the situation. These words all begin with "ex." If you don't intend to indicate exclusion, use "accept."